Method for producing thermoplastic elastomer composition

ABSTRACT

A thermoplastic elastomer composition which is excellent in balance of properties such as mechanical properties and thermal properties and in appearance is prepared by melt-kneading (A) 20-58 parts by weight of a saturated polyester resin and (B) 42-80 parts by weight of an epoxy group-containing ethylene copolymer and then melt-kneading 100 parts by weight of the resulting composition with (C) 0.01-20 parts by weight of a polyfunctional compound containing in one molecule at least two functional groups selected from an amino group, a carboxylic acid anhydride group, a hydroxyl group and a ##STR1## wherein both X and Y are oxygen atoms or sulfur atoms, or either X or Y is an oxygen atom and another is a sulfur atom, or (D) 0.01-9 parts by weight of a polyfunctional compound having in one molecule at least two carboxyl groups or both at least one carboxyl group and at least one functional group selected from an amino group, a carboxylic acid anhydride group, a hydroxyl group and the ##STR2## wherein X and Y are defined above.

This is a division of application Ser. No. 08/218,885, filed Mar. 28,1994, now U.S. Pat. No. 5,373,055, which is a FWC of Ser. No.07/956,470, filed Oct. 2, 1992, now abandoned, which is a FWC of Ser.No. 07/527,356, filed May 23, 1990, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates to a method for producing a novelthermoplastic elastomer composition which is flexible and tough in awide range of temperature and is excellent in balance of properties suchas mechanical properties and thermal properties and in appearance andcan be used for automobile bumpers, sound deadening gears, sports shoessoles, tubes, hoses, and the like.

Hitherto, flexible vinyl chloride resins, ethylene-vinyl acetate resins,thermoplastic urethane resins, nylon 12, polyester elastomers and thelike have been generally used as materials which provide hard rubbers orleather-like molded articles. However, flexible vinyl chloride resinshave a problem in cold resistance, ethylene-vinyl acetate resins in wearresistance, thermoplastic urethane resins in processability, nylon 12 incold resistance and polyester elastomers in hydrolysis resistance andthermal aging resistance and these must be improved.

Japanese Patent Kokai No. 61-40355 discloses a method for improvinghydrolysis resistance and thermal aging resistance of polyesterelastomers by blending block copolymer type polyester elastomers withcarboxyl group and/or epoxy group-containing olefin polymers. However,this composition is poor in balance of properties such as stiffness,heat resistance, impact resistance, oil resistance and electriccharacteristics because the polyester component is block copolymer typeelastomers.

Furthermore, Japanese Patent Kokai No. 55-137154 proposes to blendpolyalkylene terephthalates, ethyleneglycidyl methacrylate copolymersand a polyfunctional compound selected from epoxy compounds, isocyanatecompounds and carboxylic acid anhydrides.

Moreover, Japanese Patent Kokai No. 61-221260 teaches to blendthermoplastic polyesters with maleic anhydride graftedethylene-propylene random copolymers and ethylene-glycidyl methacrylatecopolymers. However, the above compositions are not satisfactory yet inbalance of stiffness, heat resistance, impact resistance and oilresistance as elastomers because the blending materials, blending ratioand blending method are not proper.

Further, Japanese Patent Kokai No. 63-113056 discloses that acomposition improved in compatibility, excellent in impact resistance atlow temperature and good in balance with stiffness can be obtained bymelt kneading a saturated polyester resin with a copolymer of anunsaturated epoxy compound and ethylene. The composition is considerablyimproved in these respects, but a further improvement in balance oflow-temperature impact resistance, heat resistance, oil resistance andstiffness is required for industrial use thereof.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a method for producinga thermoplastic elastomer composition which is excellent in coldresistance, especially impact resistance at low temperature in additionto heat resistance, wear resistance and chemical resistance which arecharacteristics of saturated polyester resins and excellent in balancebetween rubber elasticity and stiffness.

As a result of intensive research conducted by the inventors onpolyester elastomers comprising saturated polyester resins to which areadded epoxy group-containing ethylene copolymers, it has been found thatelastomers used for preparing various molded articles which areexcellent in heat resistance, wear resistance, chemical resistance, andcold resistance, especially impact resistance at low temperature and inthe balance between rubber elasticity and stiffness are obtained byblending a specific polyfunctional compound in a specific method.

That is, the present invention relates to a method for producing athermoplastic elastomer composition which comprises melt-kneading (A)20-58 parts by weight of saurated polyester resins and (B) 42-80 partsby weight of epoxy group-containing ethylene copolymers and thenmelt-kneading 100 parts by weight of the resulting composition with (C)0.01-20 parts by weight of polyfunctional compounds containing, in onemolecule, at least two functional groups selected from an amino group, acarboxylic anhydride group, a hydroxyl group and a ##STR3## (whereinboth X and Y are oxygen atoms, or sulfur atoms or either X or Y is anoxygen atom and another is a sulfur atom) or (D) 0.01-9 parts by weightof polyfunctional compounds having, in one molecule, at least twocarboxyl groups or both at least one carboxyl group and at least onefunctional group selected from an amino group, a carboxylic anhydridegroup, a hydroxyl group and the ##STR4## (wherein X and Y are as definedabove).

DESCRIPTION OF THE INVENTION

The saturated polyester resins(A) used in the present invention comprisea dicarboxylic acid component at least 40 mol % of which is terephthalicacid and a diol component. The dicarboxylic acid component other thanthe terephthalic acid includes aliphatic dicarboxylic acids of 2-20carbon atoms such as adipic acid, sebacic acid and dodecanedicarboxylicacid, aromatic dicarboxylic acids such as isophthalic acid andnaphthalenedicarboxylic acid and alicylic dicarboxylic acids such ascyclohexanedicarboxylic acid. These may be used singly or as mixturesthereof.

The diol component includes aliphatic and alicyclic glycols such asethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol,1,10-decanediol and 1,4-cyclohexanediol. These may be used singly or asmixtures thereof.

Among these saturated polyester resins (A), especially polybutyleneterephthalate or polyethylene terephthalate is desirable. Thesesaturated polyester resins (A) preferably have an intrinsic viscosity of0.5-3.0 dl/g measured at 25° C. using o-chlorophenol as a solvent. Thedesired mechanical strength is not expected with use of saturatedpolyester resins (A) having an intrinsic viscosity outside the aboverange.

The epoxy group-containing ethylene copolymers (B) which constitute anelastomeric component of the present invention are copolymers comprising(a) 50-99% by weight of an ethylene unit, (b) 0.1-50% by weight of anα,β-unsaturated carboxylic acid glycidyl ester unit or an unsaturatedglycidyl ether unit and (c) 0-50% by weight of an ethylenicallyunsaturated compound.

The unsaturated glycidyl ester and unsaturated glycidyl ether (b) abovein (B) are represented by the following formulas (1) and (2): ##STR5##(wherein R is a hydrocarbon group of 2-18 carbon atoms which has anethylenically unsaturated bond and X is --CH₂ --O--or ##STR6## Typicalexamples of the unsaturated epoxy compounds are glycidyl acrylate,glycidyl methacrylate, glycidyl itaconate, allylglycidyl ether,2-methylallylglycidyl ether and styrene-p-glycidyl ether.

Furthermore, the epoxy group-containing ethylene copolymers (B) includeter-or more copolymers of unsaturated epoxy compounds, ethylene andethylenically unsaturated compounds. As the ethylenically unsaturatedcompounds, mention may be made of α,β-unsaturated carboxylic acid alkylesters, carboxylic acid vinyl esters, olefins, vinyl ethers andstyrenes.

Preferred epoxy group-containing ethylene copolymers (B) are those whichcomprise 50-99% by weight of an ethylene unit (a), 0.1-50% by weight,preferably 0.5-20% by weight of an α,β-unsaturated carboxylic acidglycidyl ester unit or an unsaturated glycidyl ether unit (b) and 0-50%by weight of an ester unit selected from a carboxylic acid vinyl esterunit and an α,β-unsaturated carboxylic acid alkyl ester unit (c).Preferred are, for example, copolymers comprising an ethylene unit and aglycidyl methacrylate unit, copolymers comprising an ethylene unit, aglycidyl methacrylate unit and a methyl acrylate unit and copolymerscomprising an ethylene unit, a glycidyl methacrylate unit and a vinylacetate unit.

The epoxy group-containing ethylene copolymers (B) have a melt index(JIS K6760) of 0.5-100 g/10 min. If the melt index is more than 100 g/10min, mechanical properties of the resulting composition are degradatedand if it is less than 0.5 g/10 min, the copolymers are not satisfied incompatibility with saturated polyester resin.

The epoxy group-containing ethylene copolymers (B) may be produced byvarious methods, for example, a random copolymerization method in whichthe unsaturated epoxy compounds are introduced into the back-bone chainof the copolymers or a graft copolymerization method in which theunsaturated epoxy compounds are introduced as a side chain of thecopolymers. Some of the embodiments are copolymerizing the unsaturatedepoxy compounds and ethylene at 100°-300° C. under 500-4000 atm in thepresence of radical forming agents and in the presence or absence ofsuitable solvents and/or chain transfer agents, or mixing polyethylenewith the unsaturated epoxy compounds and radical forming agents andmelt-graft copolymerizing the polyethylene with the unsaturated epoxycompounds in extruders.

The polyfunctional compounds (C) used in the present invention includethose which have in one molecule at least two functional groups selectedfrom an amino group, a carboxylic anhydride group, a hydroxyl group anda ##STR7## (wherein X and Y are as defined above). Alternativepolyfunctional compounds (D) used in the present invention include thosewhich have in one molecule at least two carboxyl groups or both at leastone carboxyl group and at least one functional group selected from anamino group, a carboxylic anhydride group, a hydroxyl group and a##STR8## (wherein X and Y are as defined above). The polyfunctionalcompounds (C) and (D) have no special limitation in their molecularweight and include polymeric compounds.

Typical examples of the compounds (C) having at least two amino groupsin one molecule are as follows:

Aliphatic diamines such-as 1,6-hexamethylenediamine,trimethylhexamethylenediamine, 1,4-diaminobutane, 1,3-diaminopropane,ethylenediamine and polyether diamine; aliphatic diamine carbamates suchas hexamethylenediamine carbamate and ethylenediamine carbamate;aliphatic polyamines such as diethylenetriamine, triethylenetetramine,tetraethylenepentamine, pentaethylenehexamine, ethylaminoethylamine,methylaminopropylamine, 2-hydroxyethylaminopropylamine,aminoethylethanolamine, 1,3-bis(3-aminopropoxy)-2, 2-dimethylpropane,1,3,6-trisaminomethylhexane, iminobispropylamine,methyliminobispropylamine and bis(hexamethylene)triamine; alicyclicpolyamines such as menthanediamine, N-aminoethylpiperazine,1,3-diaminocyclohexane, isophoronediamine andbis(4-amino-3-methylcyclohexyl)methane; aliphatic polyamines havingaromatic ring such as m-xylylenediamine andtetrachloro-p-xylylenediamine; aromatic amines such asm-phenylenediamine, diaminodiphenyl ether, 4,4'-methylenedianiline,diaminodiphenyl sulfone, benzidine, 4,4'-bis(o-toluidine),4,4'-thiodianiline, o-phenylenediamine, dianisidine,methylenebis(o-chloroaniline), 2,4-toluenediamine,bis(3,4-diaminophenyl)sulfone, diaminoditolyl sulfone,4-chloro-o-phenylenediamine, 4-methoxy-6-methyl-m-phenylenediamine andm-aminobenzylamine; polyamines containing silicon such as1,3-bis(y-aminopropyl)-1, 1,3,3-tetramethyldisiloxane; amine-modifiedsilicone oil; butadiene-acrylonitrile copolymers having a terminalfunctional group of amine; tertiary amine compounds such asN,N,N',N'-tetramethylhexamethylenediamine andN,N,N',N",N"-pentamethyldiethylenetriamine; ethylene copolymerscomprising ethylene unit and α,β-unsaturated carboxylic acidN,N-dialkylaminoalkyl ester unit such as copolymer of ethylene andN,N-dimethylaminoethyl methacrylate; ethylene copolymers comprisingethylene unit and N,N-dialkylaminoalkyl α,β-unsaturated carboxylic acidamide unit such as copolymer of ethylene andN,N-dimethylaminopropylacrylamide; dihydrazide compounds such assuccinic acid dihydrazide, adipic acid dihydrazide, isophthalic aciddihydrazide and eicosanediacid dihydrazide; diaminomaleonitrile andmelamine. Furthermore, epoxy resin curing agents such as2,4,6-tris(dimethylaminomethyl)phenol and imidazoles e.g.,2-ethyl-4-methylimidazole may also be used.

Compounds (C) containing at least two carboxylic acid anhydride groupsin one molecule include ethylene copolymers comprising ethylene unit andmaleic anhydride unit, copolymers of isobutylene and maleic anhydrideand copolymers of styrene and maleic anhydride. These copolymers mayadditionally contain α,β-unsaturated carboxylic acid alkyl esters orcarboxylic acid vinyl esters as copolymer component. Examples of suchadditional components are alkyl esters of acrylic acid or methacrylicacid such as methyl acrylate, ethyl acrylate, butyl acrylate, methylmethacrylate, ethyl methacrylate and butyl methacrylate, vinyl acetateand vinyl propionate. Further examples are trimellitic anhydride,pyromellitic anhydride and ethylene glycol bis(anhydrotrimellitate).

As compounds (C) having at least two hydroxyl groups in one molecule,mention may be made of saponification products of ethylene-vinyl acetatecopolymer, cyanuric acid, phenolic novolak resin and o-cresol novolakresin.

The compounds (C) having at least two ##STR9## (wherein X and Y are asdefined above) in one molecule include heterocyclic compounds, aromaticcompounds and aliphatic compounds. As the heterocyclic compounds,mention may be made of, for example, parabanic acid, alloxan,alloxantin, alloxan-5-oxime, barbituric acid, 5,5-diethylbarbituricacid, 5-ethyl-5-phenylbarbituric acid,5-(1-methylbutyl)-5-allylbarbituric acid, 5,5-diallylbarbituric acid,and isocyanuric acid, and compounds in which the oxygen atom of the##STR10## in these compounds is substituted with a sulfur atom such as2,4-dithiobarbituric acid and 2-thiobarbituric acid. As the aromaticcompounds, mention may be made of, for example, pyromellitic aciddiimide, mellitic acid triimide, and 1,4,5,8-naphthalic acid diimide andthe corresponding thioimides. As the aliphatic compounds, mention may bemade of, for example, triuret, 1-methyltriuret, 1,1-diethyltriuret andtetrauret and the corresponding thiourets.

The polyfunctional compounds (D) having two or more carboxyl groups inone molecule are, for example, aliphatic polyvalent carboxylic acidssuch as oxalic acid, succinic acid, adipic acid, azelaic acid, sebacicacid, dodecanedicarboxylic acid, carbarylic acid,cyclohexanedicarboxylic acid, cyclopentanedicarboxylic acid,ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer,ethylene-acrylic acid-methyl acrylate copolymer, ethylene-acrylicacid-ethyl acrylate copolymer, ethylene-acrylic acid-butyl acrylatecopolymer, ethylene-acrylic acid-vinyl acetate copolymer,ethylene-methacrylic acid-methyl methacrylate copolymer,ethylene-methacrylic acid-ethyl methacrylate copolymer,ethylene-methacrylic acid-butyl methacrylate copolymer, andethylene-methacrylic acid-vinyl acetate copolymer, and aromaticpolyvalent carboxylic acids such as terephthalic acid, isophthalic acid,o-phthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylicacid, trimesic acid and trimellitic acid. Aliphatic polyvalentcarboxylic acids are especially preferred.

The polyfunctional compounds (D) which have in one molecule both atleast one carboxyl group and at least one functional group selected froman amino group, a carboxylic anhydride group, a hydroxyl group and the##STR11## (wherein X and Y are as defined hereinbefore) are4-aminobutyric acid, 6-aminohexanoic acid, 12-aminododecanoic acid,4-hydroxybutyric acid, 6-hydroxyhexanoic acid, 12-hydroxydodecanoicacid, 5-hydroxybarbituric acid, 5-aminobarbituric acid and5-hydroxyiminobarbituric acid.

The polyfunctional compounds (C) may be used singly or in combination oftwo or more. So are the polyfunctional compounds (D).

In the thermoplastic elastomer composition of the present invention anamount of the saturated polyester resins, the component (A), is 20-58parts by weight and that of the epoxy group-containing ethylenecopolymers, the component (B), is 42-80 parts by weight. More preferredcomposition contains 35-58 parts by weight of the polyester resincomponent (A) and 42-65 parts by weight of the epoxy group-containingethylene copolymer component (B). If an amount of the saturatedpolyester component (A) is less than 20 parts by weight, compositionsobtained have structures far from the desired one and are inferior inheat resistance and oil resistance. If an amount of the saturatedpolyester component is more than 58 parts by weight, the compositionsobtained are not sufficient in stiffness and cold resistance, especiallyimpact resistance and flexibility at low temperatures.

An amount of the polyfunctional compounds of the component (C ) or (D)should be controlled depending on reactivity thereof with the epoxygroups. So far as the polyfunctional compounds (C) having an aminogroup, a carboxylic anhydride group, a hydroxyl group or a ##STR12##(wherein X and Y are as defined hereinbefore) are concerned, an amountthereof is 0.01-20 parts by weight every 100 parts by weight of the sumof the saturated polyester resins (A) and the epoxy group-containingethylene copolymers (B). If an amount of the polyfunctional compounds(C) is less than 0.01 part by weight, an improvement in mechanicalproperties such as impact resistance is not sufficient enough, while ifit is more than 20 parts by weight, not so much improvement is obtained.The component (D), namely, the polyfunctional compounds having acarboxyl group, is added in an amount of 0.01-9 parts by weight every100 parts by weight of the sum of the components (A) and (B), sincereactivity thereof with the epoxy groups is higher than that of thepolyfuctional compounds (C). If an amount of the component (D) is lessthan 0.01 part by weight, mechanical properties of compositions obtainedare not sufficient and if it is more than 9 parts by weight, thecompositions are too reactive to be processed and the resulting articlesare inferior in various properties.

Generally speaking, an increase in impact resistance rather brings abouta decrease in stiffness, heat distortion resistance and oil resistance.According to the present invention, stiffness, heat distortionresistance and oil resistance of the composition obtained are increasedas well as impact resistance due to the polyfunctional compounds of thecomponent (C) or (D) which are blended in a specific manner. This effectof improvement is beyond expectation.

The theremoplastic elastomer composition of the present invention isprepared by kneading the components in molten state mentioned below.

The method comprises first melt-kneading the saturated polyester resincomponent (A) and the epoxy group-containing ethylene copolymercomponent (B) and, then adding to the resulting composition thepolyfunctional compound component (C) or (D) and melt-kneading them allto carry out a partial crosslinking reaction. It is assumed that theaddition and melt-kneading of the polyfunctional compound component (C)or (D) brings local crosslinking and micro-dispersion of polymers havinggood properties, with the result that an remarkable improvement inproperties is obtained.

The melt-kneading is carried out by kneading apparatuses familiar to theskilled in the art such as single- or twin-screw extruders and othervarious extruders, Banbury mixer, rolls and various kneaders.

Addition and melt-kneading of the component (C) or (D) of thepolyfunctional compounds is performed, for example, in such a mannerthat the polyfunctional compound component (C) or (D) is added to acomposition which has been melt kneaded and granulated and made from thesaturated polyester resin component (A) and epoxy group-containingethylene copolymer component (B) and then melt-kneading the mixturecomposition in extruders. Preferably, extruders with side feed devicesare used where, at the former stage (feeding side), a melt-kneadedcomposition of the saturated polyester resin component (A) and the epoxygroup-containing ethylene copolymer (B) is produced and thereto is addedsolid or molten polyfunctional compound component (C) or (D), at thelatter stage (extrusion side) of the same extruders, through the sidefeed devices and melt-kneaded. Alternatively, the polyfunctionalcompound component (C) or (D) and resins which are inert to thecomponent (C) or (D) are previously melt-kneaded to prepare amaster-batch a suitable amount of which may be added at any stage in theproduction of the present thermoplastic resin composition.

Before kneading, the resin components in the form of powder or pelletmay be homogeneously mixed by apparatuses such as tumblers or Henschelmixers. If necessary, the components may be separately fed in givenamounts to kneading apparatuses without said previous mixing.

The resin composition of the present invention may further contain, asfar as its processability and properties are not damaged, othercomponents such as, for example, pigments, dyes, reinforcing agents,fillers, heat stabilizers, antioxidants, weathering agents, nucleatingagents, lubricants, antistatic agents, fire retardants, plasticizers andother polymers.

Especially when reinforcing agents or fillers such as surface-treatedglass fibers, carbon fibers, talc and calcium carbonate are added to theresin composition of the present invention, materials high in both thestiffness and impact resistance can be obtained.

The kneaded resin composition of the present invention is molded byvarious methods such as injection molding, extrusion molding and thelike.

Modulus in bending (JIS K7203) of the resulting molded articles of resincomposition which are obtained by molding the melt kneaded resincomposition according to the present invention is preferably 500-15000kg/cm .

The object of the present invention is to provide a flexible and toughthermoplastic elastomer which is used for automobile parts such asbumpers, articles for daily use such as sports shoes and work shoes, andmechanical parts such as tubes and hoses and a modulus in bending of500-15000 kg/cm is suitable therefor. If modulus in bending is less than500 kg/cm², the molded articles are too soft and are not suitable forthe uses aimed at by the present invention and if it is more than 15000kg/cm², stiffness is too high and such articles are also not suitablefor the uses.

The following nonlimiting examples will explain the present invention.

Properties referred to in the examples were measured in the followingmanners.

Heat distortion resistance (heat sag): Sample was held by cantilever andleft to stand in a hot-air oven of 100° C. for 2 hours and deflection inthis case was measured. (Shape of the sample: 100×20×2 mm thick).

Modulus in bending: JIS K7203 (thickness of sample: 2 mm ).

Tensile strength at break and tensile elongation at break: JIS K6301(thickness of sample: mm).

Izod impact strength: JIS K7110 (thickness of sample: 4 mm; measuringtemperature: -20° C.; with V-notch). NB is at least 50 kg cm/cm and thismeans that the test specimen was not broken.

Melt index: JIS K6760 (190° C., 2160 g).

Oil resistance: JIS K6301 (The sample was dipped in lubricating oil No.3 at 70° C. for 22 hours and increment of weight was measured.).

In examples and comparative examples, the following were used assaturated polyester resins (A), epoxy group-containing ethylenecopolymers (B) and polyfunctional compounds (C) and (D).

(A) Saturated polyester resins:

(1) Polybutylene terephthalate (PBT)

PBT (1)

1401-X06 (Toray Industries, Inc.)

PBT (2)

JULANEX 200FP (Polyplastics Co.)

(2) Polyethylene terephthalate (PET)

MA-1204 (Unitika, Ltd.)

(B) Epoxy group-containing ethylene copolymers:

(1) Copolymer (1)

E/GMA/MA=66/7/27% by weight, MI=17 g/10 min.

(2) Copolymer (2)

E/GMA/MA=70/9/21% by weight, MI=19 g/10 min.

(3) Copolymer (3)

E/GMA/MA=68/2/30% by weight, MI=6 g/10 min.

(4) Copolymer (4)

E/GMA/EA=66/7/27% by weight, MI=8 g/10 min.

(5) Copolymer (5)

E/GMA/MA=75/0/25% by weight, MI=37 g/10 min.

(C) Polyfunctional compounds:

(1) Compound (1)

A copolymer of E/DAM=72/28% by weight and MI=100 g/10 min. prepared byhigh-pressure radical polymerization.

(2) Compound (2)

A copolymer of E/DAM=85/15% by weight and MI=65 g/10 min. prepared byhigh-pressure radical polymerization.

(3) Compound (3)

A copolymer of E/MAH/EA=72/3/25% by weight and MI=35 g/10 min. preparedby high-pressure radical polymerization.

(4) MB-1

A masterbatch prepared by melt-kneading 5 parts by weight ofhexamethylenediamine carbamate and 95 parts by weight of ACRYFT® WH303(Sumitomo Chemcial Co., Ltd.) at 200° C. by a 30 mmφ single-screwextruder with a vent. (ACRYFTQ® WH303 is an ethylene copolymer ofE/MMA=82/18% by weight and MI=7 g/10 min. prepared by high-pressureradical polymerization).

(5) MB-2

A masterbatch prepared by melt-kneading 5 parts by weight of isocyanuricacid and 95 parts by weight of ACRYFT® WH303 by the same method as inthe above (4).

(D) Polyfunctional compounds:

(1) Compound (4)

A copolymer of E/AA=80/20% by weight and MI=250 g/10 min. prepared byhigh-pressure radical polymerization.

(2) MB-3

A masterbatch prepared by melt-kneading 20 parts by weight of compound(4) and 80 parts by weight of ACRYFT® WH303 at 200° C. by a 30 mmφsingle-screw extruder with a vent.

(3) MB-4

A masterbatch prepared by melt-kneading 5 parts by weight of adipic acidand 95 parts by weight of ACRYFT® WH303 by the same method as in theabove (2).

(4) MB-5

A masterbatch prepared by melt-kneading 5 parts by weight ofterephthalic acid and 95 parts by weight of ACRYFT® WH303 by the samemethod as in the above (2).

(5) MB-6

A masterbatch prepared by melt-kneading. 5 parts by weight of12-aminododecanoic acid and 95 parts by weight of ACRYFT® WH303 by thesame method as in the above (2).

In the above, the abbreviations stand for the following:

E: Ethylene; GMA: Glycidyl methacrylate;

MA: Metyl acrylate; MAH: Maleic anhydride;

DAM: Dimethylaminoethyl methacrylate;

MMA: Methyl methacrylate; EA: Ethyl acrylate;

AA: Acrylic acid; MI: Melt index.

EXAMPLES 1-4

Saturated polyester resin and epoxy group-containing ethylene copolymeras shown in Table 1 were melt-kneaded, at 240° C. by a 30mmφsingle-screw extruder with a vent to obtain resin compositions.

To these compositions were added polyfunctional compounds shown in Table1 and each of the mixures was again melt-kneaded at 240° C. by a 30 mmφsingle-screw extruder with a vent to obtain elastomer compositions.

Each of the elastomer compositions was dried at 120° C. for 3 hours antherefrom a test piece for measurement of properties was prepared by a10 oz injection molding machine (Toshiba IS-150-V) at a moldingtemperature of 250° C. and at a mold temperature of 80° C.

Heat distortion resistance, modulus in bending, tensile strength atbreak, elongation, Izod impact strength and oil resistance of theresulting test pieces are shown in Table 1.

Comparative Examples 1, 2 and 4

Examples 1, 4 and 5 were repeated except that the polyfunctionalcompound (C) was not added and properties measured are shown in Table 1.The test pieces were low in stiffness, insufficient in impact resistanceand poor in oil resistance.

Comparative Example 3

Saturated polyester resin, epoxy group-containing ethylene copolymer andpolyfunctional compound as shown in Table 1 were simultaneouslymelt-kneaded at one stage at 240° C. by a 30 mmφ single-screw extruderwith a vent to obtain resin compositions. The compositions wereevaluated in the same manner as in Example 1 and the results are shownin Table 1. They were insufficient in impact resistance and inferior inoil resistance.

Examples 5-15 and Comparative Example 5

Saturated polyester resin and epoxy group-containing ethylene copolymeras shown in Table 1 were melt-kneaded by a 30 mmφ twin-screw extruderhaving a side feed and a vent during which the polyfunctional compoundas shown in Table 1 was added in a constant amount from the side feedprovided halfway of barrel of the extruder and melt-kneaded to obtainelastomer compositions. These elastomer compositions were evaluated inthe same manner as in Example 1 and the results are shown in Table 1.

Comparative Example 6

Example 12 was repeated except that a copolymer containing no epoxygroup was used as component (B).

                                      TABLE 1                                     __________________________________________________________________________    Composition               Heat         Tensile    Izod Oil resis-             (A)        (B)     (C)    distortion                                                                            Modulus                                                                            properties impact                                                                             tance in               (part      (part   (part  resistance                                                                            in   Strength                                                                           Elongation                                                                          strength                                                                           No. 3 oil              by         by      by     100° C. × 2 hr                                                           bending                                                                            at break                                                                           at break                                                                            (Kgcm/                                                                             70° C. 22                                                              hr                     weight)    weight) weight)                                                                              (mm)    (Kg/cm.sup.2)                                                                      (Kg/cm.sup.2)                                                                      (%)   cm)  (%)                    __________________________________________________________________________    Example 1                                                                           PBT (1)                                                                            copolymer (1)                                                                         compound (1)                                                                          6      3900 220  130   NB   15                           45   45      10                                                         Example 2                                                                           PBT (1)                                                                            copolymer (1)                                                                         MB-1   11      5900 230  140   NB   26                           45   45      10                                                         Compar-                                                                             PBT (1)                                                                            copolymer (1)                                                                         --     105     1000  91  130   50   Unmeasurable           ative 45   55                                          (dissolved)            Example 1                                                                     Compar-                                                                             PBT (1)                                                                            copolymer (1)                                                                         --     90      2700 100  120    6   Unmeasurable           ative 50   50                                          (dissolved)            Example 2                                                                     Compar-                                                                             PBT (1)                                                                            copolymer (1)                                                                         compound (1)                                                                         20      3800 180    80  20   45                     ative 45   45      10                                                         Example 3                                                                     Example 3                                                                           PBT (1)                                                                            copolymer (2)                                                                         compound (1)                                                                          8      3500 200  150   NB   28                           45   45      10                                                         Compar-                                                                             PBT (1)                                                                            copolymer (2)                                                                         --     85      2800 110  130    8   Unmeasurable           ative 50   50                                          (dissolved)            Example 4                                                                     Example 4                                                                           PBT (1)                                                                            copolymer (1)                                                                         compound (2)                                                                         13      4900 190  150   NB   19                           43   52       5                                                         Example 5                                                                           PBT (2)                                                                            copolymer (1)                                                                         compound (3)                                                                         12      5900 140  100   NB   18                           45   45      10                                                         Example 6                                                                           PBT (2)                                                                            copolymer (1)                                                                         MB-2   35      2500 130  175   NB   30                           35   55      10                                                         Example 7                                                                           PBT (2)                                                                            copolymer (1)                                                                         MB-3    9      6400 188  175   NB    6                           45   45      10                                                         Compar-                                                                             PBT (2)                                                                            copolymer (1)                                                                         compound (4)                                                                         Preparation was impossible                          ative 45   45      10     due to excess reaction                              Example 5                                                                     Example 8                                                                           PBT (1)                                                                            copolymer (1)                                                                         MB-4   18      2700 149  175   NB   33                           35   55      10                                                         Example 9                                                                           PBT (2)                                                                            copolymer (1)                                                                         MB-4   10      4900 191  250   NB   11                           45   45      10                                                         Example 10                                                                          PBT (2)                                                                            copolymer (1)                                                                         MB-5   21      1700 139  175   NB   34                           35   55      10                                                         Example 11                                                                          PBT (2)                                                                            copolymer (1)                                                                         MB-6   15      3300 160  175   NB   20                           35   55      10                                                         Example 12                                                                          PBT (2)                                                                            copolymer (2)                                                                         MB-4   22      1900 165  150   NB   41                           35   55      10                                                         Example 13                                                                          PBT (2)                                                                            copolymer (3)                                                                         MB-4   13      2500 141  200   NB   17                           35   55      10                                                         Example 14                                                                          PBT (2)                                                                            copolymer (4)                                                                         MB-4   12      3700 173  200   NB   27                           35   55      10                                                         Compar-                                                                             PBT (2)                                                                            copolymer (5)                                                                         MB-4   Unmeasurable                                                                          2800  96  100   NB   Unmeasurable           ative 35   55      10                                  (dissolved)            Example 6                                                                     Example 15                                                                          PET  copolymer (1)                                                                         MB-4   35      5000 175  175   NB   18                           45   45      10                                                         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As explained above, the thermoplastic elastomer composition obtained bythe method of the present invention provides very good balance inproperties of molded articles such as mechanical properties and thermalproperties and besides provides molded articles of good appearance.

Especially, addition of the polyfunctional compounds (C) or (D) canimprove stiffness and heat distortion resistance without damaging impactresistance. This is an unexpectable effect.

The novel flexible elastomer composition provided by the presentinvention can be easily processed into molded articles and sheets byprocessing methods ordinarily used for general polyester elastomers suchas injection molding and extrusion molding and the thus obtainedarticles are extremely good in balance of properties such as heatresistance, wear resistance, flexibility, impact resistance and chemicalresistance and have superior appearance and surface smoothness.

We claim:
 1. A method for producing a thermoplastic elastomercomposition having a modulus in bending of 500-15,000 kg/cm² whichcomprises melt-kneading (A) 20-50 parts by weight of polybutyleneterephthalate consisting of a terephthalic acid component and a1,4-butane diol component and (B) 50-80 parts by weight of an epoxygroup-containing ethylene copolymer comprising (a) 50-99% by weight ofan ethylene unit, (b) 0.1-50% by weight of an α,β-unsaturated carboxylicacid glycidyl ester unit or an unsaturated glycidyl ether unit and (c)0-50% by weight of an ethylenically unsaturated compound unit and thenmelt-kneading 100 parts by weight of the resulting composition with (D)0.01-9 parts by weight of a polyfunctional compound containing in onemolecule at least two carboxyl groups or at least one carboxyl group andat least one functional group selected from the group consisting of anamino group, a carboxylic anhydride group, a hydroxyl group and a##STR13## wherein both X and Y are oxygen atoms or sulfur atoms oreither X or Y is an oxygen atom and another is a sulfur atom with theproviso that when the polyfunctional compound (D) is a heterocycliccompound it contains a ##STR14##
 2. A method according to claim 1,wherein the polyfunctional compound, the component (D), is adicarboxylic acid.
 3. A method according to claim 1, wherein thepolyfunctional compound, the component (D), is an ethylene copolymercomprising an ethylene unit and an α,β-unsaturated carboxylic acid unitor an ethylene copolymer comprising an ethylene unit, an α,β-unsaturatedcarboxylic acid unit and an unsaturated carboxylic acid alkyl esterunit.
 4. A method according to claim 1, wherein the polyfunctionalcompound, the component (D), has a carboxyl group and an amino group.